Muslim armies would usually isolate the city from the rest of the region and deploy scouts along vital routes.

But for Iran, the gulf shipping is the vital route for about 1.8 billion barrels of oil a day.

The trade unions were a vital route in and that route needs to be reopened.

Hangu Pass was also a vital route in invading the ancient capital of Luoyang from the west.

Australia's Qantas, hammered by a 50% drop in business on its vital long-haul routes, was the one exception.

The reconstruction of this vital route was finally finished in 2008.

Gas, oil, and other supplies come through two vital routes: Iran and Georgia.

The area serves as a vital migratory route and resting place for countless species of birds.

Cross-sector consultancy offers a vital route to the transfer of technology between sectors of industry.

This industrial action brought very serious disruptions to flows of freight through this vital trans-European route.